二分法查找一个数问题

#include <stdio.h> 
void main()
{int a[10]={1,2,5,7,8,9,11,14,16,20};
 int x,low=0,high=9,middle=(low+high)/2,k;
 scanf("%d",&x);
   while(low<=high)
   {
   	if(x==a[middle]) {k=middle;break;}
   	  else  if (x>a[middle]) low=middle+1;
   	     else  high=middle-1;
   	middle=(low+high)/2; 
   }
 if (low>high) printf("该数组无此数");
 else printf("查找的数在数组的位置是：%d",k) ;


}